diff --git a/Userland/Libraries/LibWeb/CSS/CSSStyleSheet.cpp b/Userland/Libraries/LibWeb/CSS/CSSStyleSheet.cpp
index 18c5ce62c1..8d572e722c 100644
--- a/Userland/Libraries/LibWeb/CSS/CSSStyleSheet.cpp
+++ b/Userland/Libraries/LibWeb/CSS/CSSStyleSheet.cpp
@@ -14,9 +14,9 @@
 
 namespace Web::CSS {
 
-CSSStyleSheet* CSSStyleSheet::create(JS::Realm& realm, CSSRuleList& rules, MediaList& media, Optional<AK::URL> location)
+WebIDL::ExceptionOr<JS::NonnullGCPtr<CSSStyleSheet>> CSSStyleSheet::create(JS::Realm& realm, CSSRuleList& rules, MediaList& media, Optional<AK::URL> location)
 {
-    return realm.heap().allocate<CSSStyleSheet>(realm, realm, rules, media, move(location)).release_allocated_value_but_fixme_should_propagate_errors();
+    return MUST_OR_THROW_OOM(realm.heap().allocate<CSSStyleSheet>(realm, realm, rules, media, move(location)));
 }
 
 CSSStyleSheet::CSSStyleSheet(JS::Realm& realm, CSSRuleList& rules, MediaList& media, Optional<AK::URL> location)
diff --git a/Userland/Libraries/LibWeb/CSS/CSSStyleSheet.h b/Userland/Libraries/LibWeb/CSS/CSSStyleSheet.h
index d08e9035c2..09de9aa5a7 100644
--- a/Userland/Libraries/LibWeb/CSS/CSSStyleSheet.h
+++ b/Userland/Libraries/LibWeb/CSS/CSSStyleSheet.h
@@ -24,7 +24,7 @@ class CSSStyleSheet final
     WEB_PLATFORM_OBJECT(CSSStyleSheet, StyleSheet);
 
 public:
-    static CSSStyleSheet* create(JS::Realm&, CSSRuleList& rules, MediaList& media, Optional<AK::URL> location);
+    static WebIDL::ExceptionOr<JS::NonnullGCPtr<CSSStyleSheet>> create(JS::Realm&, CSSRuleList& rules, MediaList& media, Optional<AK::URL> location);
 
     virtual ~CSSStyleSheet() override = default;
 
diff --git a/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp b/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
index 6d4ca036b6..609439247e 100644
--- a/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
+++ b/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
@@ -128,7 +128,7 @@ CSSStyleSheet* Parser::parse_as_css_stylesheet(Optional<AK::URL> location)
     }
 
     auto rule_list = CSSRuleList::create(m_context.realm(), rules).release_value_but_fixme_should_propagate_errors();
-    return CSSStyleSheet::create(m_context.realm(), rule_list, *MediaList::create(m_context.realm(), {}), move(location));
+    return CSSStyleSheet::create(m_context.realm(), rule_list, *MediaList::create(m_context.realm(), {}), move(location)).release_value_but_fixme_should_propagate_errors();
 }
 
 Optional<SelectorList> Parser::parse_as_selector(SelectorParsingMode parsing_mode)
@@ -7398,7 +7398,7 @@ CSS::CSSStyleSheet* parse_css_stylesheet(CSS::Parser::ParsingContext const& cont
 {
     if (css.is_empty()) {
         auto rule_list = CSS::CSSRuleList::create_empty(context.realm()).release_value_but_fixme_should_propagate_errors();
-        return CSS::CSSStyleSheet::create(context.realm(), rule_list, *CSS::MediaList::create(context.realm(), {}), location);
+        return CSS::CSSStyleSheet::create(context.realm(), rule_list, *CSS::MediaList::create(context.realm(), {}), location).release_value_but_fixme_should_propagate_errors();
     }
     CSS::Parser::Parser parser(context, css);
     return parser.parse_as_css_stylesheet(location);